The present disclosure relates to online collaboration services. Online collaboration services enable multiple users or entities to interactively communicate, exchange ideas, and otherwise participate with each other over a given network. Users can interact with each other by interfacing with various computing devices such as desktop computers, mobile phones, televisions, and other interactive devices. Collaboration services can enable communication to various mediums or combinations of communication mediums, and typically operate within a given active session, forum, or virtual room. For example, such collaboration services can include chat sessions or similar messaging systems that enable participants to exchange textual information or submit comments related to a current subject of interest. In another example, a given collaboration service provides videoconferencing in which participants can see and communicate with each other. Other collaboration services enable participants to enter drawing strokes or markup a shared graphical display, similar to writing on a group white board or chalkboard. Another conventional collaboration service is known as Web conferencing. Web conferencing interfaces often combine two or more communication mediums within a single graphical user interface or display, such as by simultaneously displaying regions for video display, graphical illustration, and chat messaging. Collaboration services are distinct from passive communication models. Passive communication models, such as information broadcasts or multicasts, function for recipients that simply receive a data transmission without establishing an active connection for interaction among other recipients. Collaborative services provide a participatory communication model.